The sweat lodge (also called sweat house, medicine lodge, or medicine house) is a ceremonialsauna and an important ritual used by some North American First Nations or Native American peoples. There are several styles of sweat lodges that include a domed or oblong hut similar to a wickiup, a teepee, or even a simple hole dug into the ground and covered with planks or tree trunks. Stones are typically heated in an exterior fire[1] and then placed in a central pit in the ground. Often the stones are granite and they glow red in the dark lodge.

Rituals and traditions vary from region to region and tribe to tribe. They often include prayers, drumming, and offerings to the spirit world. Often easier methods are discovered and used, such as using a lighter to start the fire, and using a truck to haul wood and rocks. Even the use of a pitch fork, shovel, and canvas would not be of the oldest traditions. These ceremonies can change over time as certain needs arise. A sweat lodge can be a part of, or a beginning component of another, longer ceremony such as a Sun Dance. Some common practices and key elements associated with sweat lodges include:

Orientation – The door usually faces the fire, forming a duality between the lodge and the fire. This duality is, in many traditions, symbolic of the male-female or heaven-earth dualities. Directions usually have distinct symbolism in Native American ceremonies. The lodge may be oriented within its environment for a specific purpose; for example, a lodge constructed near a lake could be run with the intention of connecting to the spirit of the lake. Placement and orientation of the lodge within its environment often facilitates the ceremony's connection with the spirit world.

Construction – The lodge is generally built with great care and with respect to the environment and to the materials being used. Many traditions construct the lodge in complete silence, some have a drum playing while they build, other traditions have the builders fast during construction. Often, tobacco is placed in each hole made into the Earth and prayed over before the willow pole is placed.

Clothing – In traditional lodges, participants are naked. In more comtemporary lodges participants wear a simple brief garment or towel and nudity is most common with male only lodges. Where aversion to nudity is stronger, and where traditions vary, participants may be more fully clothed.

Offerings – Tobacco, sweet grass, redcedar or white cedar, and other plants are often used to make prayers, give thanks or make other offerings. They can be smoked in a stone pipe, sprinkled on the hot stones or offered to the fire. Prayer ties are also made in many traditions to set the intention of the lodge, show gratitude, purify one's self before the lodge, summon support from the spirit world, and other such purposes.

Support – In many traditions, one or more persons (sometimes called "dog soldiers") will remain outside the sweat lodge to protect the ceremony, and assist the participants. Sometimes they will help tend the fire and place the hot stones, though usually this is done by a designated firekeeper. In another instance, a person that sits in the lodge, next to the door, is charged with protecting the ceremony, and maintaining lodge etiquette.

The most important part of sweat lodge etiquette is respecting the traditions of the lodge leader. Some lodges are done in complete silence, while others involve singing, chanting, wailing, drumming, or other sound. It is important to know what is allowed and expected before entering a lodge. Traditional tribes hold a high value of respect to the lodge. In some cultures, objects, including clothing, without a ceremonial significance are discouraged from being brought into the lodge. The tenet is: enter the lodge as you came into this world. Alternately, other traditional tribes place a high value on modesty as a respect to the lodge. In clothed lodges, women are usually expected to wear skirts or short-sleeved dresses of a longer length. In some traditions, nudity is forbidden in mixed sex sweats. In other traditions mixed gender sweats are forbidden. Still others encourage, if not require, mixed gender sweats. Many lodge leaders do not allow menstruating women (these women are often referred to as being on their moon-time) to participate in ceremonies. Some will run a separate lodge for menstruating women. Still others allow them into the lodge after they have completed a purifying ritual, such as making a belt of prayer ties. Perhaps the most important piece of etiquette is gratitude. It is important to be thankful to the people joining you in the lodge, and those helping to support the lodge.

Wearing metal jewelry can be dangerous as metal objects may become hot enough to burn the wearer. Contact lenses and synthetic clothing should not be worn in sweat lodges as the heat can cause the materials to melt and adhere to eyes, skin, or whatever they might be touching. Cotton clothing is recommended for lodges.

Although the temperature in a sweat lodge can exceed that of a conventional sauna, partakers in a ceremony can stay inside for several hours at a time. Some argue that this is due to the ceremonial nature of the lodge. However, emphasis is placed on knowing one's own limits and knowing when to leave. There have been reports of lodge-related deaths resulting from overexposure to heat, dehydration, and smoke inhalation. Even people who are experienced with sweats could suddenly experience problems due to underlying health issues. It is recommended that a physician check people intending to have a sweat lodge experience.

If rocks are used, it is important not to use river rocks, or other kinds of rocks with air pockets inside them. Often, igneousbasalt is the best type of rock to employ. Rocks must be completely dry before heating. Rocks with air pockets or excessive moisture will likely crack and possibly explode in the fire or when hit by water. This can result in razor-sharp fragments and splinters striking participants with sufficient force to effect injury. Even rocks used before may absorb humidity or moisture leading to cracks and or shattering.

There is also a risk posed by modern chemical pesticides. When sweet grass, cedar, or certain other plants are sprinkled on the hot rocks, any pesticides accumulated on them can be turned into airborne toxins. These toxins can then be inhaled by the participants. In the past, the potential for the inhalation of carcinogenic chemicals was not well known.